Posts tagged: amp

Gorf repair log – no sound


Repair cost:  Approx. $3 (Some parts replaced unnecessarily, should’ve only been $1 fix)

KLOV Post:

Symptom: No sound

Diagnosis: 2A fuse blown on power brick.  Check all fuses, then sound amp circuit.


  • 9/21/09 – Replaced 2A fuse, no change.  Pulled sound amp board and found a Kemet 15uf 20V tantalum cap at C1 shorted & 2 fried resistors at R1 & R4 with flame/smoke marks above them.  Although the resistors tested in spec, I replaced anyway.
  • 9/26/09 – Replaced C1, sound is back, but garbled and staticky.
  • 10/11/09 – Swapped in a buddy’s working amp board, sounds awesome, so it is the amp board for sure.  Replaced TIP31 power transistors on mine, no change.
  • 10/12/09 – Tested voltages, got 16v at all critical locations on board, according to schematic.  Replaced CR1/CR2 with a 1N4007, no change.  The diodes at these points are actually piggybacked with a glass-encapsulated monolithic capacitor.  104Z (.1uf 50v) axial ceramic caps on order.
  • 10/24/09 – Replaced axial ceramic caps piggybacked at CR1/CR2, and volume pots, no change.  Checked R1/R4 again, and realized I replaced with 330 Kohm resistors instead of 330 ohm.  Replaced with appropriate value resistors & sound is back.  A few unnecessarily replaced parts here, but leaving them on because board sounds better than it did before repair!